(188 days)
Stethophone v1 is intended for medical diagnostic purposes only. It may be used for detection and amplification of sounds from the heart and lungs with the use of selective frequency ranges. It can be used on adults undergoing physical assessment.
Stethophone v1 is an electronic stethoscope software application that operates on smartphones. Stethophone v1 allows for the capture and amplification of chest sounds that are listened in real-time or recorded, cloud storage of sound records, sound filtering for selected frequency ranges, and visualization to assist in sound analysis.
Stethophone v1 is designed to assist healthcare providers to hear and visualize heart and lung sounds during a physical examination of a patient as well as storing recorded sounds for later analysis. Stethophone v1 is a decision support device used for the assessment of chest sounds of adult patients in clinical and non-clinical environments. Key product features:
- Acquiring sound through the smartphone microphone
- Real-time listening of chest sounds
- Recording of chest sounds
- Two modes of sound visualization: oscillogram and spectrogram
- Selecting among three sound filters for listening:
- Bell: Classic filter used for low frequency sounds
- Diaphraqm: Classic filter used for higher frequency sounds of heart and lungs
- Starling: Filter for listening to the full frequency of chest sounds
Here's a breakdown of the acceptance criteria and the study proving the Stethophone v1 device meets them, based on the provided FDA 510(k) summary. I will extract the relevant information and present it in the requested format.
It's important to note that this document is a 510(k) summary for a substantial equivalence determination, not a full clinical study report. Therefore, some details typically found in a comprehensive clinical trial description (like specific statistical methods for power calculation, detailed blinding procedures, or a full MRMC breakdown) might not be present or as detailed as one would expect from a dedicated clinical study publication.
Acceptance Criteria and Device Performance
The document states that Sparrow Acoustics Inc. submitted performance testing information "to validate that the device meets predetermined specifications and performs according to pre-specified acceptance criteria." However, it does not explicitly list a table of acceptance criteria with corresponding performance metrics. Instead, it describes various tests conducted to support safety and efficacy.
Based on the nature of the device (an electronic stethoscope software) and the information provided, the acceptance criteria would revolve around:
- Acoustic Performance: Ability to accurately capture, amplify, and filter heart and lung sounds within specified frequency ranges.
- Functional Performance: Real-time listening, recording, playback, sound visualization (oscillogram, spectrogram), filter selection, volume control, and smartphone compatibility.
- Usability: Ease of use for healthcare providers.
- Safety: No electrical safety or electromagnetic compatibility issues (due to being standalone software).
Given the absence of a specific table, the "reported device performance" is inferred from the claims of "substantially equivalent" and the successful completion of the described tests.
Here is a conceptual table based on the provided text, outlining the implied acceptance criteria and the claimed performance.
Table 1: Implied Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific (Implied) Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Acoustic Performance | Capture and amplify sounds between 20 and 2000 Hz. | Stethophone v1 "picks up and amplifies the sound between 20 and 2000 Hz." |
| Specific frequency emphasis for Bell filter (25-300 Hz). | Bell filter "emphasizes range from 25 to 300 Hz." | |
| Specific frequency emphasis for Diaphragm filter (170-850 Hz). | Diaphragm filter "emphasizes frequency spectrum range 170-850 Hz." | |
| Specific frequency emphasis for Starling filter (60-1400 Hz). | Starling filter "works between 60-1400 Hz." | |
| Functional Performance | Real-time listening of chest sounds. | "Real-Time Auscultation: Yes" - Confirmed. |
| Recording of chest sounds. | "Record and Playback Sounds: Yes" - Confirmed. Recording length of 20 seconds. | |
| Two modes of sound visualization (oscillogram and spectrogram) | "Sound Visualization: Yes" - Confirmed. "Available Sound Visualization: Spectrogram, oscillogram." | |
| Selection among three sound filters (Bell, Diaphragm, Starling). | "Filter Selection: Yes" - Confirmed. Offers three specific filters. | |
| Volume control functionality. | "Volume Control: Yes" - Confirmed. | |
| Compatibility with specified iPhone models. | Compatible with a broad range of iPhone models from 6s to 13 Pro Max. | |
| Usability | User-friendly interface for healthcare providers. | "Usability and performance study conducted by an independent medical facility" was performed to support equivalence claims, implying satisfactory usability. No specific metrics like SUS scores or task completion rates are provided. |
| Safety | No electrical safety or electromagnetic compatibility risks. | "Not Applicable (Standalone Software). Therefore, there is no source of electrical safety or electromagnetic compatibility associated directly with the device." |
| Overall Equivalence | Functionally equivalent to predicate devices for intended use. | "The proposed device Stethophone v1 and the predicate devices Steth IO and Littmann 3200 share the same intended use, design, user functions and fundamental scientific operational technology. The devices are functionally the same." Differences do not affect safety/effectiveness. |
Study Details
Here's a breakdown of the study details as presented in the 510(k) summary:
-
Sample sizes used for the test set and the data provenance:
- The document mentions "performance tests using an anechoic chamber," "internal tests run by a medical analysts' team," "tests involving external medical specialists with auscultation experience," and "a usability and performance study conducted by an independent medical facility."
- However, specific sample sizes (e.g., number of audio recordings, number of subjects for usability, etc.) for any of these test sets are NOT explicitly stated in this summary.
- Data Provenance: Not explicitly stated, but the company is Canadian (Sparrow Acoustics Inc., Lucasville, NS, Canada). The nature of the tests (internal, external specialists, independent facility) suggests some form of prospective testing for performance and usability. It does not mention retrospective data analysis.
-
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The document refers to "a medical analysts' team" and "external medical specialists with auscultation experience."
- The exact number of experts and their specific qualifications (e.g., "radiologist with 10 years of experience" or "cardiologist") are NOT specified. It only indicates "auscultation experience," which is a broad term.
-
Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- The document does NOT describe any specific adjudication method (like "2+1" or "3+1 consensus") for establishing ground truth from the medical analysts or specialists. It simply states that they were involved in internal and external testing.
-
If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- A formal MRMC comparative effectiveness study in the sense of comparing human readers with AI assistance versus without AI assistance was NOT described or implied.
- The testing focused on the device's standalone performance, its acoustic properties, and its usability, aiming to demonstrate substantial equivalence to predicate devices, not improvement of human readers. The device is described as a "decision support device" but the efficacy study is not structured as an MRMC human-in-the-loop study.
-
If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, performance of the device's sound capturing, amplification, and filtering capabilities were evaluated, including "performance tests using an anechoic chamber." This can be considered a form of standalone testing for the device's acoustic properties.
-
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- For the acoustic performance testing (e.g., anechoic chamber), the "ground truth" would be established by controlled sound inputs and calibrated measurement equipment.
- For the tests involving "medical analysts' team" and "external medical specialists," the ground truth likely involved the clinical judgment or consensus of these experts regarding the quality, clarity, and diagnostic utility of the sounds captured and presented by the Stethophone v1 compared to their auscultation experience with predicate devices. No pathology or outcomes data is mentioned.
-
The sample size for the training set:
- The Stethophone v1 is described as an "electronic stethoscope software application" that provides "sound filtering for selected frequency ranges, and visualization to assist in sound analysis." It is not described as an AI/ML algorithm that requires a training set in the traditional sense (i.e., for learning patterns for classification or prediction).
- It functions as an audio processing and visualization tool. Therefore, a training set in the context of machine learning is not applicable or mentioned for this device. Its "training" would be more akin to software development and acoustic engineering calibration.
-
How the ground truth for the training set was established:
- As there is no mention of a traditional machine learning "training set" for the Stethophone v1, this question is not applicable based on the provided document. The device's functionality relies on signal processing and displaying capabilities, not on learned patterns from a labelled dataset.
§ 870.1875 Stethoscope.
(a)
Manual stethoscope —(1)Identification. A manual stethoscope is a mechanical device used to project the sounds associated with the heart, arteries, and veins and other internal organs.(2)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.(b)
Electronic stethoscope —(1)Identification. An electronic stethoscope is an electrically amplified device used to project the sounds associated with the heart, arteries, and veins and other internal organs.(2)
Classification. Class II (special controls). The device, when it is a lung sound monitor, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.